The high cost of currently available single optical photon imaging equipment is limiting the development of a variety of important instruments and assays based on bioluminescent and chemiluminescent reactions. We propose the development of a device that will enable low cost single photon imaging with an anticipated dynamic range up to 10^9 and spatial resolution down to 50 microns at the input window. The device developed in Phase I will utilize a hybrid structure consisting of a large area, high gain avalanche photodiode placed behind an 18mm Generation III photocathode in vacuum tube device. Performance will be evaluated in the 400-900nm region. Phase II will adapt the manufacturing process to a larger format tube which accepts the proprietary Imaging Avalanche Photodiode that we have developed. Bialkali and S-20 photocathodes for sub-400nm imaging will also be evaluated in Phase II. In Phase III, the developed device will be integrated into a variety of instruments that perform assays based on single optical photon imaging. PROPOSED COMMERCIAL APPLICATIONS: Markets for the device to be developed in this project and for instruments based on the device are estimated to be the range of $16-21 million per year. This market includes instruments for basic research, high throughput luminescent assay analysis and food industry diagnostics. Markets for luminescence based gene chips and non-imaging detectors are also considered.